Visit Trader Johann' Ship to trade in resources for Collection Items.  If you enter and see the Secret Speed Sales, either take advantage of these offers or chose skip to see the Collectibles he has to offer for you.
The cost for these items vary between resources. A new loot will be available every time the timer runs out, or until the player pays the required Runes. Some collection item have different backgrounds. You need to collect not only the correct item, but also the correct background which is required in your Collection.